Design of ultrasonic transducers for use with rolling mill rolls

ABSTRACT

A HOLLOWED OUT ROLLER FROM A ROLLING MILL WITH AN ULTRASONIC TRANSDUCER PLACED WITHIN THE OPENING. THE TRANSDUCER IS A CIRCULAR ELECTROMAGNETIC OR A PIEZOELECTRIC TYPE WHICH CREATES VIBRATIONS THAT RADIATE OUTWARD FROM THE CENTER OF THE ROLLER. TO WITHSTAND EXCESSIVE VIBRATIONAL FORCES, THE ULTRASONIC TRANSDUCER IS EITHER RABBIT JOINTED OR EXPOXIED INTO POSITION WITHIN THE ROLLER.

Nov. 16, 1971 J. w. CUNNINGHAM ETAL 3,620,061

DESIGN OF ULTRASONIC TRANSDUCERS FOR USE WITH ROLLING MILL ROLLS Filed Oct. 5, 1969 37 INVENTORS JAMES M CUNNINGHAM GEORGE R. DOUGLAS ATTORNEY United States Patent O s 620 061 DESIGN OF ULTnAsoNic TRANSDUCERS FOR USE WITH ROLLING MILL ROLLS James W. Cunningham, Vandergrift, and George R. 5

Douglas, Pittsburgh, Pa., assignors to the United States of America as represented by the Secretary of the Navy Filed Oct. 3, 1969, Ser. No. 863,480 Int. Cl. B21b 27/00 US. Cl. 72-199 3 Claims ABSTRACT OF THE DISCLOSURE A hollowed out roller from a rolling mill with an ultrasonic transducer placed within the opening. The transducer is a circular electromagnetic or a piezoelectric type which creates vibrations that radiate outward from the center of the roller. To withstand excessive vibrational forces, the ultrasonic transducer is either babbit jointed or epoxied into position within the roller.

STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION This invention relates to a method and means of rolling metal stock into sheets, and more particularly, to the use of ultrasonic vibratory energy to reduce the loading required during the rolling process.

The use of ultrasonic vibratory energy in a metal forming process has been well known in the art for many years. The adaptation of such energy to the rolling mill process, however, has been fairly recent. The many problems inherent in adapting an ultrasonic vibrational source to a mill roller being used in a mill which is exerting a force of 300,000 lbs. or greater have not yet been completely solved. Specific problems that up to the time of this invention have been left with unsatisfactory solutions are, inefficient coupling between the vibrational source and the roller, the manufacture of a vibrational source capable of producing the intensity of ultrasonic energy required, and producing an ultrasonic vibrational source that has a long operating life.

SUMMARY OF THE INVENTION By use of a cylindrical ultrasonic transducer of the magnetostrictive or piezoelectric type placed within the roller of a rolling mill, maximum coupling between the roller and the metal being rolled is obtained. The use of a babbit joint in the case of the electromagnetic transducer and a high strength epoxy in the case of the piezoelectric transducer to bond the respective transducers to the hollowed out segment of the roller, insures a long operating life for the respective transducer. Loading was found to be reduced the most when displacement of the roller occurs perpendicular to the rolling direction and the roller surface. A circular transducer creates this type of vibrational displacement when placed within a roller. By using the circular type of ultrasonic vibrational transducer within a roller of a rolling mill, therefor, an excep- Patented Nov. 16, 1971 "ice OBJECTS OF THE INVENTION An object of this invention is to provide a rolling mill roller that requires less loading to perform the desired effect.

Another object of this invention is to provide a rolling mill roller that requires less loading because of vibrational energy supplied by an ultrasonic transducer placed within the roller.

A still further object of this invention is to provide a roller with an ultrasonic transducer which will have a long working life and not require an excessively high power source.

Yet another object of this invention is to provide a method for rolling metal which does not require as much loading force as prior art devices.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration, partly broken away, of a roller within which is located a vibrational transducer;

FIG. 2 is an end view the roller of FIG. 1 which illustrates the means used to fasten the roller sections to gether;

FIG. 3 is a diagrammatical illustration of a magnetostrictive wagon wheel transducer used in the roller; and

FIG. 4 is a diagrammatical illustration of a piezoelectric ceramic ring transducer as used within the roller.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wagon wheel magnetostrictive or a ring type piezoelectric transducer is placed within a central hole bored into a standard roller which is used in an 8 x 8 two highfour high Stanat mill or other well known rolling mill. The roller is adapted by cutting out the central section, placing the transducer into this central section, and bolting the central and two end sections back together. Before the roller is bolted back together, the transducer is bonded to the interior of the central section by means of a babbit joint with respect to the magnetostrictive wagon wheel transducer, and by means of epoxy with respect to the piezoelectric transducer. The feed cables for the transducer are directed from the transducer to the source through a small hole bored into the end sections of the roller. The construction and placement of the transducer causes the vibrational action to be delivered to the roller surface and in turn to the metal being rolled in a more eflicient manner than was heretofore possible with prior art devices. The coupling utilized between transducer and roller permits more eflicient energy transfer from transducer to the metal working surface, in turn making pos sible the use of a smaller power source.

Referring now to the figures Where like members represent like parts in the different views, referring first to FIG. 1, the roller 10 has been partly broken away to show its interior. As can be seen from FIG. 1, the roller comprises three sections, a central section 11, and two end 3 sections 12 and 13. Shoulders 24 and 23 are part of end section 12 and shoulders 20 and 21 are part of end section 13. Shoulders 24 and 21 are squared off so as to fit the square drive of a rolling mill. Shoulders 23 and 20 are cylindrical, as is the rest of the roller.

Central section 11 has bored within it, along its symmetrical axis, an opening 14. The bore 14 has a diameter which is approximately of the diameter of the central section 11. Each of the end sections of the roller have bored within them a respective opening along their axis of symmetry. These bores 15 and 16 are of a diameter sufficient to permit power cables access to the transducer placed within the opening 14. The three sections of the roller are held together by a plurality of bolts such as 18 and 19 which are circumferentially placed about the axis of symmetry of the roller. These bolts are of sufficient strength and quantity to allow the roller to be used safely up to a mill separating force of 200,000 lbs.

FIG. 2 more clearly illustrates the placement of these bolts. As can be seen from FIG. 2, bolts 19 are placed circumferentially around the axis of symmetry of the entire roll. Numeral 23 of FIG. 2 is the circular shoulder of the roller and 24 of FIG. 2 is the square driving shoulder.

Referring now to FIG. 3, a magnetostrictive transducer 28 is diagrammatically illustrated. The design of this magnetostrictive transducer is the result of much experimentation. The wagon-wheel design was chosen because it of fered the most surface to volume ratio and therefore more eflicient cooling of the transducer would occur. Also, the wagon-wheel design would result in a more efficient vibration source because of its solid center. These advantages of the wagon-wheel transducer are brought forth when making a comparison with a cylinder type of magnetostrictive transducer. FIG. 3 is an end view of transducer 28. Transducer 28 comprises a stack of laminations formed in the manner shown by form 29. The laminations are made of 2V Permendur material which was chosen for having a longer operating life and being capable of obtaining higher power levels. The magnetostrictive properties of Permendur material are described on page 86 of Ultrasonic Technology, written by Goldman, and published by Reinhold, 1922. The leg 30 of the transducer lamination set 29 is split as shown by line 32.

Laminations such as 29, that make up the transducer body are approximately .004 inch in thickness and soldered midway along the roll body. The stack of laminations that make up the transducer is joined to the roller body by the use of a babbit joint which comprises a mixture of 84% Sn-8% Sb-8% Cu. This joint was found to be superior in performance to Pb-l% Sb solder or silver epoxy.

Winding 31 and the rest of the windings illustrate the winding scheme of the transducer. Each winding, such as winding 31, consists of wire, wound twenty turns per inch. The four wound legs are connected in series.

Referring now to FIG. 4 which illustrates, in cross section, the center section 11 of the roller 10, having a bore 14. Placed within the bore 14 is a plurality of radially poled ceramic rings 34. The rings are made of lead-zirconate-titanate ceramic and are machined so as to fit very closely together. They are bonded to the roller interior at ground electrode side 35 and between themselves by epoxy bonds. They are snugged into the bore by means of Teflon spacers such as 37 on each end of the stack Power source leads, brought into opening 14. are con nected to the radially poled piezoelectric rings at high potential electrode surface 36 of the respective rings. Radially poled ceramic rings were used instead of axially poled ceramic rings because the radially poled rings were found to have improved high voltage breakdown properties.

Experiments were conducted with the magnetostrictive and piezoelectric transducer rollers of this invention. The power source used to drive the ultrasonic transducers was capable of kv.-a. at 600 volts over a frequency range of 5 to kHz. Intermittent rather than continuous power application was used during the rolling cycle. When using a single magnetostrictive roller, an average of 23% load reduction occurred on lead having a thickness ranging from .077 inch to .260 inch. It was found that no appreciable load decrease Was obtained for aluminum metal stock having an average thickness of 1.5 inches. When the piezoelectric transducerized roller was used, a load reduction of approximately 41% was noticed when rolling lead ranging in thickness from .16 inch to .30 inch. A load reduction of approximately 4% was noticed when aluminum stock ranging in thickness from .16 inch to .30 inch was used. The static load reduction when using the piezoelectric transducerized roll on lead stock was approximately 47%. When aluminum stock was used, the static load decrease was approximately 3.6%.

The above percentages were the result of the use of one piezoelectric transducerized roller. Experiments were conducted using two piezelectric transducerized rollers. When rolling aluminum stock, it was found that the general trend was for a greater percentage of rolling load decrease as the initial thickness of the aluminum stock or/ and its initial width was decreased.

The average percentage load decrease observed when rolling copper stock was approximately 14% for stock ranging in thickness from .046 inch to .063 inch.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings.

What is claimed is:

1. A roller for use in rolling metal stock into sheets comprising:

a solid central cylinder having a central opening extending axia'lly therethrough;

two solid end cylinders disposed at a respective end of said central cylinder, each of said end cylinders having a central opening extending axially therethrough and formed to driveably connect to a standard rolling mill and fasten to said central cylinder by a plurality of bolts;

a cylindrical wagon-wheel magnetostrictive transducer that produces ultrasonic vibrations perpendicular to said roller surface and said roller direction disposed Within said opening of said central cylinder and bonded thereto by a babbit joint so as to transmit ultrasonic energy radially outward through said central cylinder; and

cables physically and electrically connected to said transducer and physically extended to an outside driving source through said opening of said end cylinders.

2. A roller for use in rolling metal stock into sheets comprising:

a solid central cylinder having a central opening extending axially therethrough;

two solid end cylinders disposed at a respective end of said central cylinder, each of said end cylinders having a central opening extending axially therethrough and formed to driveably connect to a standard rolling mill and fasten to said central cylinder by a plurality of bolts;

a cylindrical piezoelectric transducer that produces ultrasonic vibrations perpendicular to the roller surface and rolling direction disposed within said opening of said central cylinder and bonded thereto by an epoxy joint so as to transmit ultrasonic energy radially outward through said central cylinder, said piezoelectric transducer comprising a plurality of radially poled ceramic rings in stacked intimate contact with each other and Teflon spacers on each end of the stack of rings to help prevent electrical breakdown; and

cables physically and electrically connected to said transducer and physically extended to an outside driving source through said opening of said end cylinders.

3. The roller recited in claim 2 wherein said piezoe'lectric transducer comprises seven lead-zirconate-titanate radially poled rings.

References Cited UNITED STATES PATENTS 6 FOREIGN PATENTS 133,324 10/1951 Sweden 72-l99 OTHER REFERENCES 5 Black, Ultrasonics Research Promises Production Payoff," Machinery, October 1967, pp. 95-97.

MILTON S. MEHR, Primary Examiner US. Cl. X.R. 

